The present disclosure relates to a developer conveying device and a developing device and an image forming apparatus provided with the same.
Conventionally, a developing device in which an agitating screw is mounted in a developer housing is known as a developer conveying device for conveying developer. The agitating screw of the developing device is composed of a shaft portion and a spiral piece arranged around the shaft portion. In the developer housing, the developer is conveyed in a predetermined conveying direction by driving and rotating the agitating screw.
If an adhesion force of the developer increases with the deterioration of the developer, the developer may adhere to the shaft portion. If the developer adheres to the shaft portion, virtual shaft thickening of the agitating screw occurs to reduce the conveying performance of the agitating screw. To solve the shaft thickening of the agitating screw described above, some developing devices use an agitating screw including no shaft part, i.e. having a hollow shape in an axial central part thereof.
With the above agitating screw, the developer being conveyed in the hollow part of the agitating screw may aggregate in the developer housing. Such aggregation of the developer becomes notable in a high-temperature environment and when the developer is deteriorated. Particularly, in the agitating screw having the hollow shape, the developer may cylindrically aggregates.
An object of the present disclosure is to suppress the cylindrical aggregation of developer in a hollow part in a developer conveying device including a developer conveying member having a hollow shape.